1.9Tdi glow plugs are not needed unless temperatures drop below 7c.
The ECM keeps an eye on glow plug current draw. If it detects a difference in draw, it will turn the check engine light on and set
one or more glow plug Fault codes.
Do you have any stored codes?
If no codes, then the ECM thinks that all is fine.
The temp sensor is located on the side of the cylinder head. In the coolant flange.
Post a picture of your engine (with the cover removed) and I will tell you where to look.
Disconnecting the temp sensor for testing purposes is OK, but it will set a temp sensor code when you do so.
You might have other issues (carbon build-up in the intake that is preventing enough air from getting into the cylinders, in order
to get a hot enough compression to start the engine (without the glow plugs).
Check your intake.
I look forward to your reply.
Saturday, December 15th, 2012 AT 9:31 PM